This invention in one aspect relates to preparing non-terminally substiututed alkane phosphonic acids. These acids are useful as detergent composition additives. (See Zimmerer U.S. Pat. No. 3,351,558 and Jacobsen Ser. No. 709,015 filed July 27, 1976, and Jacobsen Ser. No. 728,579 filed Oct. 1, 1976).
This invention in another aspect relates to preparing internally unsaturated olefins (the term "internally unsaturated olefins" is used herein to mean olefins with unsaturation other than in the 1-position; it does not necessarily imply a thermodynamic equilibrium mixture; it does not include dimer and other telomers). Internally unsaturated olefins are useful as intermediates in the preparation of the non-terminally substituted derivatives in general as well as the alkane phosphonic acids specifically mentioned above.
Various methods of producing non-terminally substituted alkane phosphonic acids are known in the patent literature, but none of such methods is very suitable for a commercial process.
For example, the Zimmerer patent referred to above discloses a preparation involving reaction of a paraffin, phosphorus trichloride and oxygen followed by hydrolysis. One of the major problems associated with this preparation is production of product with a high percentage of phosphonate groups in the 1-position (approximately 16%). Another serious problem associated with this preparation is severe foaming in the hydrolysis step.
The Zimmerer patent also discloses a preparation involving isomerizing alpha olefin by use of iron pentacarbonyl and then adding phosphorous acid to the isomerized olefins using gamma radiation as a souce of radicals. Major shortcomings of this preparation are the requirement of flammable and/or toxic solvents and the lack of availability of sufficient gamma radiation for commercial manufacture.
The Zimmerer patent also discloses a process involving radical addition of diisopropyl phosphites to internally unsaturated olefins followed by pyrolysis. There is a severe corrosion problem associated with the pyrolysis step of this process in relation to metal reaction vessels and an etching and corrosion problem in relation to glass lined metal vessels.
It is an object of this invention to provide a novel process for producing such acids where production of 1-phosphonates is minimized, where foaming does not occur, where usage of solvent is not required, where gamma radiation is not required, and where etching and corrosion problems are insignificant.
It is also an object of one embodiment of this invention to provide a novel process for isomerization of alpha olefins where conversion to internally unsaturated isomers is very high while dimer formation is minimized.